Previous inventions were designed to provide cardiac-pulmonary bypass as an assistance to the heart and allow the heart to work continuously even there is significant compromise of blood supply to the heart, or to replace the function of the heart when it fails to function. For example, U.S. Pat. No. 4,540,399 to Litzie discloses a cardiopulmonary bypass machine. It allows a physician to control the speed of the pump to maintain blood pressure at a certain level. U.S. Pat. No. 5,879,316 to Safar also discloses a cardiopulmonary bypass machine, which provides differential perfusion of different organs including the heart. It considers selective perfusion of the heart as a part of resuscitation and allows the heart to stop for one to two hours. However, it requires a complicated procedure.
A design of a pump was made public (Tokano H. et. al, World J. Surgery 9:78-88, 1985), which has EKG gating and left arterial pressure feed back to control work load on the heart. The left arterial pressure is used to determine the work load on the heart and, therefore, to control pump activity for unloading volume from the left ventricle. It is also a left ventricular assistant device and allows the heart to continue to contract and to assume a central role in circulation.
A number of inventions have disclosed cardiopulmonary bypass machines for open-heart surgery. They require insertions of a catheter into the heart chambers and the great blood vessels surgically and extensive technical support.
If a machine can maintain blood pressure, a physician can put the heart into asystole, or near asystole, without significant compromise to the function of the organs. Patients can survive without the heart's functioning, and the heart survives until a definitive treatment takes place. The heart has enough time to recover from a transient myocardial insult.